Single umbilical artery: incidence, clinical significance and relation to autosomal trisomy.

In a study of 2500 consecutive births at the Women's Pavilion, Winnipeg General Hospital, a single umbilical artery was found to be present in 0.2% of all births. This is considerably less than the incidence of 1% of all births quoted in the literature. We believe the lower figure more representative of the true incidence. The association of a single umbilical artery with multiple congenital malformations is confirmed, and in addition there appears to be a significant association of late maternal age and low birth weight in the group in which a single umbilical artery was found. The finding of a single umbilical artery in three of six cases of autosomal trisomy is noted. Routine examination of the cord in all births is indicated, and the presence of a single umbilical artery should alert the physician to the possibility of the presence of congenital malformation which may not be clinically evident on ordinary examination of the newborn infant.